# Function call speedup (CV applied to functions)

- Thread: https://externals.io/message/26782
- Original archive: https://news-web.php.net/php.internals/26782
- Started by Sara Golemon on 2006-12-04T05:48:44+00:00
- Messages: 5
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## #26782 — Sara Golemon — 2006-12-04T05:48:44+00:00

URL: https://externals.io/message/26782#26782

It's been a concept stuck in my mind since I first looked into ZE2.1 and 
saw what compiled variables were, and a recent blog post 
(http://php100.wordpress.com/2006/11/24/optimizations/) (which got 
picked up by planet PHP) got my wheels spinning again.  Tonight I 
decided to actually sit down and see what benefit could be milked from 
such an endeavor and what it's maintenance cost would be.

The attached patch shows what I've tossed together for HEAD and the 
benchmark I've run against it do show some appreciable gains...

Based on this code snippet, I saw a consistent gain of aproximately 18%:
for($i = 0; $i < 10000000; $i++) `pi()`;

I chose the `pi()` function as it (A) would actually favor the unpatched 
approach, being quick to hash and strcmp.  It also (B) performs minimal 
actual work, simply returning a constant value, thus leaving as much of 
the execution time to the matter being tested as possible.

Of course, this isn't a "normal use" example, and it doesn't address 
dynamic function calls or method calls.  I also havn't looked into class 
resolution yet, but this is a good spot to begin discussion from.

Thoughts anyone?

-Sara

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## #26794 — Ilia Alshanetsky — 2006-12-04T16:09:24+00:00

URL: https://externals.io/message/26782#26794 · In reply to: #26782

Looks fairly interesting, I doubt 18% is consistent benefit across  
the board, and when unicode overhead is removed is probably less  
still. But, it does look like a good optimization to make that would  
certainly make PHP faster then before.

Ilia Alshanetsky

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## #26796 — Sara Golemon — 2006-12-04T16:40:33+00:00

URL: https://externals.io/message/26782#26796 · In reply to: #26794

> Looks fairly interesting, I doubt 18% is consistent benefit across the 
> board
>
I doubt it very much too.  While I made that test to strip out non-fcall 
overhead, I also made it favor the effect being produced by constantly 
calling the same function from the same scope.  Reality isn't like that.

> and when unicode overhead is removed is probably less still.
My numbers were based on unicode.semantics=off just FYI...

> it does look like a good optimization to make that would certainly make 
> PHP faster then before.
> 
I suspect optimized class fetches will help several cases too:
foo::bar();
foo::baz(foo::BLING);

Just not going to bother working on that unless it sounds worth doing to 
enough people.

-Sara

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## #26798 — Ilia Alshanetsky — 2006-12-04T16:46:00+00:00

URL: https://externals.io/message/26782#26798 · In reply to: #26796

> > […]
> I doubt it very much too.  While I made that test to strip out non- 
> fcall overhead, I also made it favor the effect being produced by  
> constantly calling the same function from the same scope.  Reality  
> isn't like that.
>
> > […]
> My numbers were based on unicode.semantics=off just FYI...

That's good, although unicode based PHP does have a number of  
additional checks not present in non-unicode version (not-PHP6).

> > […]
> I suspect optimized class fetches will help several cases too:
> foo::bar();
> foo::baz(foo::BLING);

Only for native classes though.

Ilia Alshanetsky

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## #26812 — Dmitry Stogov — 2006-12-06T12:57:02+00:00

URL: https://externals.io/message/26782#26812 · In reply to: #26782

Hi Sara,

Interesting patch.

We had very similar idea in the past.
BTW it is possible to optimize function calls mach more.
Not only ZEND_DO_FCALL but also ZEND_INIT_FCALL_BY_NAME can be optimized,
and we can reuse the same cache entries for all op_arrays from the same PHP
file.

I'll make a patch and send it to you in fey days.

Thanks. Dmitry.

> -----Original Message-----
> From: Sara Golemon [mailto:pollita@php.net] 
> Sent: Monday, December 04, 2006 8:49 AM
> To: internals@lists.php.net
> Subject: [PHP-DEV] Function call speedup (CV applied to functions)
> 
> 
> It's been a concept stuck in my mind since I first looked 
> into ZE2.1 and 
> saw what compiled variables were, and a recent blog post 
> (http://php100.wordpress.com/2006/11/24/optimizations/) (which got 
> picked up by planet PHP) got my wheels spinning again.  Tonight I 
> decided to actually sit down and see what benefit could be 
> milked from 
> such an endeavor and what it's maintenance cost would be.
> 
> The attached patch shows what I've tossed together for HEAD and the 
> benchmark I've run against it do show some appreciable gains...
> 
> Based on this code snippet, I saw a consistent gain of 
> aproximately 18%: for($i = 0; $i < 10000000; $i++) `pi()`;
> 
> I chose the `pi()` function as it (A) would actually favor the 
> unpatched 
> approach, being quick to hash and strcmp.  It also (B) 
> performs minimal 
> actual work, simply returning a constant value, thus leaving 
> as much of 
> the execution time to the matter being tested as possible.
> 
> Of course, this isn't a "normal use" example, and it doesn't address 
> dynamic function calls or method calls.  I also havn't looked 
> into class 
> resolution yet, but this is a good spot to begin discussion from.
> 
> Thoughts anyone?
> 
> -Sara